fuel tap issues

[Christopher]

Hello folks any advice appreciated. I rebuilt the fuel tap on my gs850 with rebuild kit. The tap now hardly flows on prime, on, or reserve and engine wont start but overflows into engine overnight and leaks with oil from somewhere onto floor. Slight amount of petrol in oil. Dropped the oil and replaced but not sure what to do now because already rebuilt tap. The bike has just been recommisioned after sitting for a few years. I have cleaned the carbs. What to check or do next? Thanks

[Christopher]

Also I have an inline fuel filter.

[Baatfam]

You need an OEM fuel tap, (petcock), the rebuild kits don't work.

And get rid of the fuel filter, not needed, and reduces flow.

Welcome to the forum...

[rphillips]

On pri. all openings should be wide open, vacuum or no vacuum. Sounds like something didn't get put back together correctly. You may want to look in the carbs/fuel/exhaust section. There's a post down there from just a couple of days ago that may help. Like he said, you shouldn't need the fuel filter if the one on the pet cock is there & in reasonable condition.

[Christopher]

Hello thanks for the advice and now I see I put question in the wrong section. I cant find an oem fuel tap from Uk sources. They are available Usa ebay for over £100 shipped and taxed. Has anyone had luck with the cheaper aftermarket ones? Can source aftermarket for £17. Do you guys think I might have carb float valve issues aswell as the tap? Cheers Christopher

[Grimly]

The cheap aftermarket ones are surprisingly nicely made, but they're rubbish at doing their job, with weak springs, etc.
My 79 tank has a rebuilt (with OEM parts) petcock and it works well. The 80 bike has an adapter plate and a Harley petcock.

[Admiral Beez]

Hello thanks for the advice and now I see I put question in the wrong section. I cant find an oem fuel tap from Uk sources. They are available Usa ebay for over £100 shipped and taxed. Has anyone had luck with the cheaper aftermarket ones? Can source aftermarket for £17. Do you guys think I might have carb float valve issues aswell as the tap? Cheers Christopher

I bought this one and it’s been fine for over two seasons now, through many a switch between prime, run and reserve.

https://www.amazon.ca/dp/B07GSXY9PD/ref=pe_1086170_134824320_cm_rv_eml_rv0_dp

Perhaps they have a UK source?

[joe penoso]

That looks original, very good and cheap. An unusual combination.
joepenoso

[Grimly]

The cheap ones are a total crapshoot.
I bought one a year or two back and while it seemed nicely made, it wouldn't shut the fuel off worth a damn. Weak spring in the diaphragm.
No point in fiddling around trying to cure it, as I'd never trust it, and should it fail in use, I really don't want a crankcase full of fuel or five gallons dribbling down the workshop overnight.
That got replaced by a strictly manual Harley aftermarket tap, on a plate adapter bolted under the tank. I'm now solidly in the habit of turning it off.

[Admiral Beez]

The cheap ones are a total crapshoot.
I bought one a year or two back and while it seemed nicely made, it wouldn't shut the fuel off worth a damn. Weak spring in the diaphragm.
No point in fiddling around trying to cure it, as I'd never trust it, and should it fail in use, I really don't want a crankcase full of fuel or five gallons dribbling down the workshop overnight.
That got replaced by a strictly manual Harley aftermarket tap, on a plate adapter bolted under the tank. I'm now solidly in the habit of turning it off.

After more than a decade riding vintage British where you always turned off the fuel tap it still rattles me when I just walk away from the GS without turning off the fuel.

[Grimly]

After more than a decade riding vintage British where you always turned off the fuel tap it still rattles me when I just walk away from the GS without turning off the fuel.

First bike I bought with an auto tap was an XS750, and it was great not having to remember to turn the tap off. Every bike since has come with them, but resurrecting the old habit took a little while. As I say, now it's become second nature again.

[Kingjoel]

Not to argue but I just installed a petcock kit from 2 fast moto ($17) and it works perfect. The diaphragm I bought first didn't work because the o-ring shaft was too short and wouldn't seal unless I bent the disc that seats in the spacer.

[dpep]

I bought this one and it’s been fine for over two seasons now, through many a switch between prime, run and reserve.

https://www.amazon.ca/dp/B07GSXY9PD/ref=pe_1086170_134824320_cm_rv_eml_rv0_dp

Perhaps they have a UK source?

This particular petcock is widely available, inexpensive, and has the right bolt pattern for 80-81 850Gs. But the fuel outlet is on the back of the petcock facing inward instead of on the front facing the engine like the OEM. Has that proved to be any kind of issue with regard to routing the fuel line? My preference is to have the port where it is more visible and accessible.
...

[rphillips]

I never remember that problem, I think the back of the valves are square so the outlet can be rotated in 4 different directions. Remember, I'm not perfect, I was wrong once, so no guarantees.

[Grimly]

Remember, I'm not perfect, I was wrong once, so no guarantees.

You were only wrong in thinking you were wrong that one time.